There are three stable forms of neon: neon-20, neon-21, and neon-22. Which statement is true?

The charge of all isotopes are the same.

Explanation:

isotopes are radioactive.

They have different numbers of neutrons resulting in different atomic mass.

Not all isotopes are equally abundant in nature.

three stable isotopes

Neon has three stable isotopes: 20Ne (90.48%), 21Ne (0.27%) and 22Ne (9.25%). Ne and 22Ne are partly primordial and partly nucleogenic (i.e. made by nuclear reactions of other nuclides with neutrons or other particles in the environment) and their variations in natural abundance are well understood.

alchemy hadn't scientific methods of study, appeal to mysticism and fantasy, the knowledge of chemistry and physics were modest at that time.

alchemy was - but as new rules were discovered it either changed into chemistry or it became "unscientific".